Distillation apparatus

ABSTRACT

A distillation apparatus which may be cleaned without having to be dismantled and which is provided with means for preventing overheating in the event of failure in the liquid feed to the boiler which apparatus comprises a boiler provided with heating means which may be shut off by a means of a thermo static switch, a condenser which feeds a resirvoir optionally fitted with a level sensing device so that operation of the apparatus only occurs when the level of distillate in the reservoir falls below a given level, and a syphon which may be actuated to drain distill and from the boiler to permit flushing of the boiler with a cleaning or de-furring liquid which is in turn drained from the boiler by the syphon.

Oct. 3, 1972 5 F, F11-CH ETAL DISTILLATION APPARATUS 5 Sheets-Sheet 1 Filed March ll, 1970 ATTORNEYS Wwf, if 1%@ Oct. 3, 1972 I s, F. FITCH EI'AL DISTILLATION APPARATUS Filed lMarch l1, 1970 5 Sheets-Sheet 2 ai. mm

n l INVENTORS STANLEY FREDERICK FITCH DARA DERRICK PHIROZ ST. JOHN 7 ATTORNEYS Oct. 3, 1972 s. F.F1TCH ETAI- 3,696,003

DISTILLATION APPARATUS Filed March l1, 1970 5 Sheets-Sheet .'5

INVENTORS STANLEY FREDERICK FITCH DARA BERRICK PHIROZ ST.JOHN

,fx'IToRNL-WS OC. 3, 1972 5, F', FWCH EVAL.

DSTILLATION APPARATUS 5 Sheets-Sheet v4 Filed March ll, 1970 a ciOlVnlOV NOHdAS AOd. 3, 1972 5, F. F11-(3H ETAL DI STILLAT ION APPARATUS 5 Sheets-Sheet 5 F'iled March ll, 1970 United (States Patent @Hice 3,696,003 Patented Oct. 3, 1972 U.S. Cl. 202-160 '8 Claims ABSTRACT OF THE DISCLOSURE A distillation apparatus which may be cleaned without having to be dismantled and which is provided with means for preventing overheating in the event of failure in the liquid feed to the boiler which apparatus comprises a boiler provided with heating means which may be shut off by means of a thermostatic switch, a condenser which feeds a reservoir optionally fitted with a level sensing device so that operation of the apparatus only occurs when the level of distillate in the reservoir falls below a given level, and a syphon which may be actuated to drain distill and from the boiler to permit ilushing of the boiler with a cleaning or de-furring liquid which is in turn drained from the boiler by the syphon.

The present invention relates to a distillation apparatus.

There is a great demand for distilled water in research and industry and, therefore, it is desirable to have a ready source available. For this reason, most laboratories distill their own water, either in a batch or continuous manner. Batch distillation is generally inconvenient and time consuming, whereas continuous distillation is more convenient provided that a number of diliiculties are overcome. One great disadvantage of continuous distillation, particularly in hardwater areas, is that the apparatus rapidly become furred owing to the deposit of calcium, magnesium and other salts, and the apparatus has to be dismantled frequently for cleaning. A further disadvantage is that, in the event of a water failure, the heating element is liable to burn out. Moreover, many continuous processes are, in fact, merely extensions of batch distillations since distillation must be manually terminated when the reservoir is full and then started again when empty or partly empty.

We have now developed a distillation apparatus which overcomes these disadvantages and automatically provides a continuous supply of distilled water.

Accordingly, in one embodiment of the present invention we provide an automatic distillation apparatus comprising a boiler vessel, heating means for heating the boiler vessel, a thermostatic switch for preventing overheating of the heating means, a first liquid feed inlet for feeding liquid to be distilled to the boiler vessel, a second liquid feed inlet for introducing cleaning or other liquid into the boiler vessel, syphon means actuatable to empty the boiler vessel, a condenser for condensing vaporized liquid issuing from the boiler, and a reservoir for receiving the condensed liquid, said reservoir including a levelsensing device responsive to the level of liquid in the reservoir and adapted to actuate a switch to turn on and off the heating means and the supply of liquid to the boiler.

The above apparatus automatically maintains a desired level of distilled liquid in the reservoir, is easy to clean and will not overheat in the event of a water failure and yet does not require constant supervision. It will be understood that although the primary application of the present invention is for the distillation of water, it is also suitable for the distillation of other liquids.

In a preferred embodiment of the present invention, the apparatus includes means for maintaining a constant level of liquid in the boiler vessel.

'Ihe boiler vessel may be of any convenient shape and size, and may be made from any suitable material, e.g. metal, plastics material or ceramics. 'It is preferred that it be made from a thermal-shook-resistant glass. The boiler may be heated by any suitable means, e.g. by a hot plate or electric mantle, but is preferably heated by an immersion heater, e.g. an electric element which is desirably sheathed and is of suitable heating capacity for the size of the boiler.

The thermostatic switch is provided to prevent overheating of the heating means in the event of a water failure. If overheating occurs, the switch serves to switch olf the heater and also the ow of liquid to the boiler. Many such switches are known and may be used, but preferably a bimetallic switch, e.g. that known as an Otter switch, is used. These switches are particularly sensitive to infra-red radiation and should preferably be placed in the boiler vessel adjacent to the heating means. In the case where the heating means is an electrical heater, the switch may cut olf the electrical supply to the heater directly. In the case where other forms of heating means are used, the switch may actuate some intermediate mechanism to cut olf the heating means, e.g. a solenoid valve which cuts olf the gas supply to a gas burner.

To prevent possible damage to the boiler or heater resulting from a sudden inflow of cold liquid into a still hot boiler when the supply of liquid is restored, the thermostatic switch preferably has a high differential so that the liquid supply cannot be switched on again until the boiler temperature has dropcd to, say, about 70 C.

The liquid to be distilled may be fed to the boiler via. the iirst feed inlet from any desired source capable of a continuous supply of liquid and a supply such as a tap linked to the water main is convenient for water distillation. Preferably, the liquid is fed at a constant predetermined rate (or pressure) and it is preferred that a device for maintaining a constant level of liquid in the boiler vessel be provided. Various such devices are known and may be used. Preferably the device is an overflow device of a conventional type.

The second feed inlet for the cleaning or other liquid may be a separate entrance port in the boiler vessel which may be closed by a stopper or tap when not in use. Alternatively, it may be provided in the form of a branch olf the first feed inlet conduit to the boiler vessel. In either case, a funnel is preferably provided to facilitate the admission of the cleaning or other liquid into the second feed inlet.

Any of the conventional syphons may be provided to empty the boiler vessel but preferably one which is primed lby a sudden jet of water, which may be introduced by switching on a solenoid valve, is used.

In a preferred form of apparatus, the syphon and deyice for maintaining the level in the boiler vessel are integral or connected and the liquid is fed to the boiler vessel via the first feed inlet by back flushing through the syphon. Where water is to be distilled, we have found it convenient to use the cooling water from the condenser as the feed water to the constant level/syphon device which then feeds the water at the desired rate to the boiler.

Any suitable condenser may be used but preferably a conventional water-cooled condenser is used. The watersupply to the condenser may be controlled by a solenoid valve which may be controlled by the thermostatic switch for the heater, or by a separate switch. The rate of water supply to the condenser is preferably adjustable by means of a flow-meter and a control associated therewith. When the apparatus is used to distill water the condenser is suitably cooled so that the distillate has a temperature of not less than 60 C., since at temperatures above 60 C., the carbon dioxide initially present in the feed water to the boiler is evolved to an appreciable extent from the distillate and can be bled off from the condenser to yield a distillate of optimum quality. The condenser should, therefore, preferably have an outlet through which the carbon dioxide evolved may be bled olf. The condenser preferably also includes an integral trap of a conventional type for removing pyrogens from the distilling liquid.

The condenser feeds a reservoir for condensed distillate and the reservoir may be of any suitable type. As indicated above, the reservoir is provided with a levelsensing device, which is preferably manometric, and suitably actuates a bellows which in turn actuates a microswitch. Alternatively, the level-sensing device may be of the ball-cock or float type which moves in response to the liquid level, such movement being used to actuate the micro-switch. The micro-switch may then act directly or indirectly, for example through a relay, to switch on or olf the heating means. The micro-switch also acts, for example, through a solenoid valve, to switch on or off the ow of liquid through the first liquid feed inlet. When the reservoir is empty (or the liquid level is below a predetermined level) the micro-switch is actuated to restore the heating and tiow of liquid to the boiler via the first liquid feed inlet is restored. Thus, the liquid in the reservoir is automatically maintained between certain predetermined levels.

In a further preferred embodiment of the present invention the apparatus is mounted in a housing which gives it the appearance of a scientific instrument and protects the apparatus from breakage and dirt. Such a housing suitably has such operating switches, lights, measuring dials and gauges as are required for operation of the apparatus mounted therein.

Such controls preferably include the following:

Orl/olf switchthis is suitably a double pole switch controlling the main power supply to the still. It is advantageously associated with a red warning lamp mounted on the housing to indicate whether it is operating.

Heater switch-this switch controls the electrical supply to the heater and the water supply to the condenser. It also acts as a manual re-set switch for the heater if the thermostatic switch has cut off the heaters electrical supply. It is desirably also associated with a signal lamp on the housing to indicate whether it is operating.

Flush switch-this switch actuates the ush solenoid valve to empty the boiler vessel by initiating the syphon in the constant level device. It may also act to back flush the boiler with water for cleaning purposes. It is preferably coupled with the heater switch such that both switches cannot be in the ON position together.

Flowmeter-this indicates the quantity of water or other cooling liquid flowing through the condenser, and is suitably coupled with a flow control knob tted to the meter, and mounted on the housing.

Tap control-this diverts the distillate stream either to the reservoir or to an outlet from which it may be collected or during the initial period following cleaning of the boiler contaminated distillate may be discarded.

The housing may also include observation ports for examining the degree of furring, or the state of the distillation, etc., and thermometers may be mounted on the housing.

It has been found that it is convenient if the reservoir and its level-sensing device are ,included in a rst housing separate from a second housing containing the distillation apparatus and the switch actuatable by the level- 4 sensing device. It has also been found useful if the second housing is arranged for mounting on the first housing.

Accordingly, from a yet further embodiment of the present invention we provide an automatic distillation apparatus comprising a boiler vessel, heating means for heating the boiler vessel, a thermostatic switch for preventing overheating of the heating means, a first liquid feed inlet for feeding liquid to be distilled to the boiler vessel, a second liquid feed inlet for introducing cleaning or other liquid into the boiler Vessel, syphon means actuatable to empty the boiler vessel and a condenser for condensing vapourised liquid issuing from the boiler.

In operation of the apparatus of the invention water is fed to the rst inlet to the boiler via the constant level device. The Water is boiled Within the boiler and the steam is passed through the condenser to give a distillate which may be collected in a reservoir or used directly. As indicated above the water from the condenser is desirably fed to the constant level device feeding the boiler, excess condensed water being allowed to run to Waste. Under normal conditions the feed of water to the boiler will be suicient to replace that distilled off. However, if this is not the case the boiler may boil dry and the resultant overheating will be detected by the thermostatic switch in the boiler which will then act to cut off the power to the boiler heater. Where the apparatus feeds a reservoir having a constant level device therein, the operation of the distillation apparatus will be on an intermittent rather than on a continuous basis according to the size and frequency of distillate removal from the reservoir.

To clean the apparatus when used for distilling water, the water supply is stopped and the syphon actuated to empty the boiler vessel or residual water. Acid is then introduced into the boiler vessel through the second feed inlet and the boiler vessel may be heated if necessary. When the fur-removal is complete, the acid is removed by means of the syphon and the boiler vessel may then be flushed out with several changes of water introduced from either the lirst or the second feed inlets and removed by the syphon. Analogous methods of cleaning the apparatus when used for the distillation of other liquids will be readily apparent, and may entail the use of aqueous and/ or organic solvents.

A preferred embodiment of the distillation apparatus of the invention will now be described with reference to the accompanying drawings, wherein like numerals refer to like parts, and in which:

FIG. 1 is a diagrammatic sectional view of a housing containing the distillation apparatus and the operating panel therefor;

FIG. 2 is a front view of a housing containing the reservoir;

FIG. 3 is a circuit diagram for operating the still;

FIG. 4 is a tlow diagram, with portions in cross-section, ilustrating liquid and vapour flow through various parts of the apparatus of the present invention;

FIG. 5 is a plan view, with portions in cross-section, of the condenser connections; and

FIG. 6 is a cross-sectional View along line 'VI-VI of FIG. 4 illustrating the inlets and outlets of the constant level/ syphon device.

As shown in FIG. l, the distillation apparatus is contained in a housing 1 having a glass boiler vessel 2 mounted therein by silicone rubber lined metal brackets 3. The boiler vessel has mounted therein at least one silica sheathed electrical heating element 4 connected to a terminal block 5, and a thermostatic switch 6. The boiler is provided with a water inlet (not visible behind the constant level/syphon device 18 but shown in FIG. 6) which also serves as the water outlet when it is desired to drain the boiler.

The boiler vessel 2 has a ground glass socket 7 which accepts a Water-cooled condenser 8 having an internal water-cooled coil shown in FIGS. 4 and 5, an integral glass trap 9 to ensure a pyrogen-free distillate, and an outlet 10 for bleeding off carbon dioxide and directing any uncondensed steam through a vent to the outside of the housing. The condenser can be connected to a main water supply through the solenoid valve 29. As shown in FIGS. 1 and 4 distillate iiows from the condenser 8, through a conduit 11 to a ow control tap, the knob of 12 of which is shown mounted on a control panel 13 formed on the housing 1. The knob 12 has two positions, in one of which the distillate flows to the reservoir (shown in FIG. 2) through conduit 14 and connection 15, and in the other of which the distillate flows to an external reservoir (not shown) through a conduit 14.

As shown in FIGS. 4 and 6, water is fed to the boiler vessel 2 via a constant level/ syphon device 18, which maintains the water level in the boiler vessel 2 constant, and a T junction in tube 16 connected to the inlet of the boiler. The device 18 may be integral with the boiler or may be mounted separately by means of a magnetic foot acting on the metal base of the housing 1. A compact apparatus is achieved by using the cooling water flowing through the condenser 8 as the feed for the device 18. Excess water in the device 18 ows out of the apparatus via side arm 19' and conduit 19 to waste. Within the device 18 is mounted an inverted glass U tube as the syphon. One end of the U tube is connected to conduit 19 via pipe 18' and the other free end has its orifice close to the point of entry of pipe 16 into device 18. The crown of the U tube is located above the level of the side arm 19' feeding conduit 19 to ensure an airlock in the U tube during normal operation `of the device 18. The boiler vessel can be emptied by initiating the syphoning action of the U tube in device 18 by means of a solenoid ush valve 20 inserted between tube 16 and tube 17. The jet of water from tube 16 enters the open end of the U tube lling the whole of the U tube with water and thus initiating its syphonic action. Cleaning liquid may be passed into the boiler vessel 2 through a funnel 21 formed integrally with the device 18, once the syphon has removed the water in the boiler.

The control panel 13 has mounted thereon main on/of press button switches 22 and a signal lamp 23 associated therewith to indicate when the apparatus is switched on. Also mounted on the panel are a heater switch 24 associated with a signal lamp 25, and a press button switch 26 for actuating the solenoid valve 20 for initiating the syphoning action of the device 18 to empty the apparatus. Beneath the signal lamp on the panel is mounted a control knob 27 for controlling the water flow to the condenser which is shown on a ow meter 28. Associated with the control knob 27 is a solenoid valve 29 in the water supply line to the condenser 8. On the rear of the panel 13 is mounted a pressure switch 30 connected, though a conduit 31, to a level sensing device 32 (see FIG. 2) in the reservoir. The pressure switch controls the main input solenoid valve 29 as well as the electrical supply to the heater 4.

The housing 1 has feet 33 and these can be inserted into locating sockets 34 of the reservoir housing 35 shown in FIG. 2. The housing 35 comprises a reservoir 36 having a viewing aperture 37 therein for viewing the distillate level, and a control panel 38 having a tap 39 mounted thereon leading to a bench outlet 39 for the distillate. The conduit 31 from the pressure switch 30 in the distillation apparatus is connected to the level sensing device 32 through a nipple 40 mounted on the device 32, and the distillate is fed to the reservoir from conduit 14 and connection 1'5 through a nipple 41 also mounted on the level sensing device 32.

Referring now to the circuit diagram of FIG. 3 the terminals L, E and N form the live, earth and neutral terminals of terminal block '5 connected to the circuit through fuses 42 and 43 linked on/ off press button switches 22, which have the signal lamp 23 connected across them.

The solenoid flush valve 20 is connected to the power 6 terminals through the push button switch 26 and thermostatic switch 6.

The heating element 4 is connected into the circuit through a relay 44, a push button heater switch 24, and the pressure switch 30. The solenoid-actuated valve 29, for the cooling feed water supply to the condenser 8, and the signal lamp 25 are connecte-d in parallel across the heating element 4. The heating; section of the circuit also includes the thermotatic switch 6, and a safety switch 45 linked to the push button switch 26 such that the boiler vessel cannot be emptied without isolating the heating element from the circuit. If further heating elements are required, these are connected in parallel with heating element 4.

In use the still is connected to a main Water supply. Switch 22 is depressed, actuating the circuit and igniting signal lamp 23. Heater switch 24 is closed which closes the relay switch 44 and actuates the heating element and the solenoid valve 29 to admit water, through the flow meter 28, to the condenser 8. The water flowing from the condenser 8 passes through the constant level/syphon device 18 via the T junction in tube 16 to the boiler vessel 2, while water in excess of that required to maintain the constant level flows to waste or recycle through conduit 19.

The distilled water passes through conduit 11 to the reservoir 36 which, when full, causes the level sensing device 32 to actuate the opening of the pressure switch 30 and thereby switching of't` the heater and water supply to the condenser. If the water supply should fail and the boiler vessel overheat, the thermostatic switch `6 opens to switch oir relay switch 44 and cut oi the heater and water supply to the condenser.

To clean or empty the boiler vessel 2 the ush solenoid valve 2t) is actuated by switch 26 causing the U tube in the device to act as a syphon. When the boiler vessel 2 is empty, cleaning liquid such as acid may be introduced through funnel 21, and the heater switch 24 may be switched on to fill the boiler with water and also to dilute the acid. The boiler vessel 2 may then be emptied as before, and the apparatus flushed out with several changes of water.

From the above description of a distillation apparatus incorporating an integrated constant level/syphon device for the boiler, such integrated devices may be generally described as being a hollow vessel having a liquid feed inlet, a liquid overflow outlet and a liquid feed outlet which is connected to the liquid feed inlet to the boiler, the vessel also being provided with a syphon adapted to remove liquid from the vessel at a level in the vessel at or below that of the liquid feed outlet and intermittently operable priming means whereby the spyhon may be initiated. Preferably the priming means is provided by a jet of water directed into the orifice of the syphon and conveniently in the device shown in FIG. 1 such a water jet is introduced into the hollow vessel by means of the tube 16 upon actuation of the valve 20. During operation of the syphon water is drained from the hollow vessel and the flow of water in the feed pipe to the boiler is reversed with water draining from the boiler to the hollow vessel.

It will be realised that the apparatus may be readily adapted to the distillation of other liquids, in which case, the water flow from the condenser passes directly to waste and the liquid to be distilled is supplied directly to the constant level device 118. Such an arrangement may also be used for distilling water if so desired.

We claim:

1. A distillation apparatus comprising a boiler vessel, heating means for heating the boiler vessel, a thermostatic switch for preventing overheating of the heating means, first liquid feed inlet for feeding liquid to be distilled to the boiler vessel, a second liquid feed inlet for introducing cleaning or other liquid into the boiler vessel, syphon means actuatable to empty the boiler vessel, a condenser for condensing vapourised liquid issuing from 7 the boiler, and a reservoir for receiving the condensed liquid, said reservoir including a level-sensing device responsive to the level of liquid in the reservoir and adapted to actuate a switch to turn on and olf the heating means and the supply of liquid to the boiler.

2. A distillation apparatus according to claim 1 wherein the reservoir and the level sensing device are mounted in a housing separate from the rest of the apparatus.

3. A distillation apparatus comprising a boiler vessel; heating means for heating the boiler vessel; a thermostatic switch for preventing overheating of the heating means; an inlet whereby liquid to be distilled may be fed to said boiler vessel, said inlet being in iluid flow communication with a constant level/syphon device adapted to maintain a constant level of liquid in said boiler vessel when in use and to remove liquid from said boiler vessel when it is desired to empty said boiler vessel, said constant level/syphon device comprising a hollow chamber member having a liquid feed inlet, a liquid overflow outlet and a liquid feed outlet which is in fluid ilow connection with the liquid feed inlet to said boiler vessel, the chamber member also being provided with a normally inoperative syphon adapted to remove liquid from the chamber member at a level at or below that of said liquid feed outlet, and intermittently operable priming means whereby the syphonic action of the normally inoperative syphon may be initiated; and a second inlet whereby cleansing or other liquid may be introduced into the boiler vessel; said boiler vessel also being provided with means for condensing vaporized liquid issuing therefrom.

4. A distillation apparatus as claimed in claim 3 wherein priming of the syphon is achieved by means of a jet of liquid directed into the orifice of the syphon.

5. A distillation apparatus as claimed in claim 4 wherein the liquid outlet is provided with a valved branch thereto whereby a jet of water may be introduced into the liquid outlet to prime the syphon.

6. A distillation apparatus for distilling water comprising a boiler provided with an electrical heating means for heating the boiler; a thermostatic switch for preventing overheating of the heating means; a water feed inlet to the boiler; a constant level/syphon device which device comprises a hollow chamber having a water feed inlet, a water overow outlet and water feed outlet, the water feed outlet being in lluid flow connection with said water feed inlet to the boiler, the hollow chamber member also being provided with a syphon adapted to remove water from the hollow chamber at a level at or below that of the water feed outlet; a water cooled condenser for condensing vaporized liquid issuing from the boiler having the cooling water outlet thereof connected to the water feed inlet to the constant level/syphon device; a second inlet whereby cleansing or other liquid may be introduced into the boiler vessel; and an intermittently operable priming means whereby the syphonic action of the normally linoperative syphon may `be initiated.

7. A distillation apparatus as claimed in claim 6 wherein the water feed outlet from the lhollow chamber is provided with a branch pipe whereby a jet of liquid may be directed at the orifice of the `syphon within the hollow chamber so as to initiate the spyhonic action of the syphon.

8. A distillation apparatus as claimed in claim 6 wherein the said second inlet is provided by a further inlet to said hollow chamber.

References Cited UNITED STATES PATENTS 339,201 4/1886 Merz 202--169 3,203,227 8/1965 Donnell 202-185 X 3,498,885 3/1970' Holm et al. 202--160 WILBUR L. BASCOMB, JR., Primary Examiner I. SUPER, Assistant Examiner U.S. Cl. XR.

202l67, 176, 177, 180, 185, 185 E, 181, 206; 203-2, 4, l 

